Flowserve TRS 5-6 - Manual (Page 8)

8
Explanatory Notes
– continued –
Function
The temperature switch type TRS 5-6 is a two channel unit provided with an
automatic periodic self-checking logic unit, in accordance with DIN 3440/VDE 0116
(regulations for protection circuits for firing equipment of furnaces). The two
channels are designed to monitor the operation of each other. If one channel fails,
an alarm signal is initiated, simultaneously switching the output contacts to shut off
the heat supply. The periodic self-checking logic unit checks the two channel
circuits for malfunction. The integrity of the resistance thermometer is continuously
monitored by the TRS 5-6. This is done automatically every 40 seconds by the
triggering of a test alarm pulse through the circuit. Unless it finds a fault, this
internal test does not interfere with the output contacts of the temperature switch
and therefore the plant operation is not interrupted.
A manual test push button is also provided. When the push button
TEST
I is pressed,
it simulates a fault in the resistance thermometer. There is also a toggle switch
TEST
II /
INSPECTION
for checking the function of the self-checking circuitry.
The output contact relays of the temperature switch are of the normally closed type
and will therefore signal alarm condition in the event of a mains failure.
The temperature switch can signal the following three operating conditions:
■ Normal operation (temperature within permissible range)
■ Alarm (limit temperature exceeded)
■ Alarm (fault in temperature switch or resistance thermometer)
A green LED indicates mains supply
ON
. Exceeding of limit temperature or
malfunction of the system is indicated by two red LEDs. The failure of one channel
(loss of redundancy) is signalled by the lighting-up of one red LED.
The combination of resistance thermometer TRG 5-... and temperature switch
TRS 5-6 provides fail-safe protection against a first fault, i. e. the system will still
continue to provide the safety function even after the occurence of a first fault.
System description
Self-monitoring temperature switch with periodic self-checking feature to be used in
conjunction with a resistance thermometer type TRG 5-53, TRG 5-54, TRG 5-55,
TRG 5-56, TRG 5-57 or TRG 5-58.
The equipment operates as a safety temperature controller, or in conjunction with an
external lock-out in accordance with VDE 0116 as a safety temperature limiter.
An alarm is given as soon as the temperature exceeds a preset limit value.
Application in steam boilers and pressurized hot-water plants operating without
constant supervision (TRD 604) as well as any other kind of heat generator.